Systems that create two-dimensional images of structures within a body under examination by launching pulses of ultrasonic carrier waves into it along different radial paths and converting any echoes of the pulses into corresponding electrical waves have been commercially available for a number of years. The images thus formed have an intensity that is proportional to the amplitude of the echoes.
In an article entitled "Ultrasonic Characterization of Myocardium" in the September/October 1985 issue of Progress in Cardiovascular Diseases, the quantitative relationship between the energy of the backscatter of ultrasonic pressure waves and the condition of myocardium is discussed. Ischemic injury is of particular interest because its early detection would provide a real-time basis for determining whether or not a patient has had a heart attack as well as its extent, whereas present techniques for simply determining whether or not a heart attack has occurred often require several days of analysis. Although not discussed in the article, it is possible that other abnormal tissue conditions could be revealed by similar analysis. Whereas the article suggests the desirability of forming a two-dimensional image having intensity corresponding to the energy of the intensity of the echoes, no viable way of achieving this objective is described. The article does suggest that the variations in brightness of the images formed in response to the amplitude of echoes, as in the available apparatus briefly described above, can give some indication of the condition of the tissue, but the variations due to such phenomenon are so small that little reliance can be placed on them.